Cirrhosinones A-H, 24-hydroxy cevanine-type alkaloids from Fritillariacirrhosa

Eight undescribed isosteroidal alkaloids cirrhosinones A-H (1-8), along with six known isosteroidal alkaloids (9-14), were isolated from the bulbs of Fritillaria cirrhosa D. Don. Their structures were determined by HRESIMS and 2D NMR analysis, and their absolute configurations were established by X-ray analysis. Compounds 1-8 possessed a typical cevanine-type alkaloid skeleton with a hydroxyl group rarely substituted at C-24 and compounds 4-8 possessed rare 7α or 7β-hydroxyl groups. This was the first report of both C-7 and C-24 hydroxyl groups substituted cevanine-type alkaloids. In addition, an approach for distinguishing D/E cis and trans conformations of cevanine-type alkaloids by ¹H NMR data was developed. Moreover, the correlations between the relative configurations of 3-OH, 7-OH, 22-C, 24-OH, and 25-Me and the ¹H NMR and ¹³C NMR data were also summarized. Compounds 1-9 exhibited moderate NO inhibitory activities in LPS-stimulated BV-2 cells at the concentration of 40 μM. The acetylcholinesterase inhibitory activities of compounds 1-7 and 9-10 were also evaluated and none of them showed acetylcholinesterase inhibitory activities at the concentrations of 20-80 μM.